Hydrogenotrophic denitrification of saline aquaculture wastewater using hollow fiber membrane bioreactor | |
| Author | Diep Dinh Phong |
| Call Number | AIT Thesis no.EV-07-9 |
| Subject(s) | Membrane reactors Bioreactors Aquaculture Water--Purification Saline water conversion plants--Waste disposal |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | High nutrient loading of wastewater discharged from aquaculture ponds into the environment causes eutrophication and affects aquatic life in receiving water bodies. This study used hollow fiber membrane bioreactor including denitrifcation reactor for hydrogenotrophic denitrification to remove nitrate followed by aerobic reactor designed for organic carbon removal. In the denitrification reactor, hydrogen was used as electron donor and CO2 was supplied to control pH and scour the hydrogen diffusing membrane. Inlet concentrations of nitrate and organic matters in terns of DOC were 50 mg/L and 20 mg/L. The experiment included the acclimatization of hydrogenotrophic bacteria to salinity of 10 ppt and three experimental runs with salinity concentrations in wastewater of 10, 20, and 30 ppt. In each run, optimum hydraulic retention time (HRT) and operating parameters was determined. Direct acclimatization method which acclimatized hydrogenotrophic denitrifiers directly to salinity of 10 ppt Was found more efficient than the stepwise acclimatization with gradual increase of salinity. Optimum hydraulic retention times in run 1, 2 and 3 were determined at 3 h, 5 h and 6 h respectively. At these HRTs, the nitrogen removal efficiency reached to more than 90% and denitrification rate of total system was 366.8, 226.2 and 193.2 g/m3.day respectively. In the denitrification tank, biomass yield Was from 0.42 to 0.48 g cells/g NO3-N and hydrogen utilization efficiency was from 61 to 84%. After denitrification stage, dissolved organic carbon (DOC) decreased by 45 - 63%, indicating that there Was the involvement of hetrotrophic denitrification in nitrate removal process. The hydrogen diffusing membrane Was operated for one month without reduction of denitrification performance caused by membrane fouling. At optimum HRTs, water quality of treated wastewater in terms of nitrate, nitrite, DOC, SS was very good. The study demonstrated that this system can treat saline aquaculture wastewater with high efficiency and good quality of treated wastewater which can be recycled to closed aquaculture ponds in practice to avoid discharge pollutants into the environment |
| Year | 2007 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Visvanathan, C. |
| Examination Committee(s) | Nguyen Thi Kim Oanh;Shipin, Oleg;Jegatheesan, Jega V |
| Scholarship Donor(s) | MOET, Vietnam - AIT fellowship |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2007 |